This invention relates to a method and apparatus for determining certain conditions of engine operation, and more particularly, to an improved method and apparatus for determining burned gas temperature and trapped mass in the combustion chamber, and for predicting NO.sub.x emissions from the engine based on the luminosity and pressure detected in the combustion chamber.
With modern technology and electronics, many of the components and running conditions of an internal combustion engine can be controlled more accurately than with previous mechanical systems. For example, the control of the air/fuel ratio, spark timing, fuel injection timing and pulse, and other adjustable factors of engine operation are greatly facilitated through the use of electronic components and computers. However, in order to accurately sense the running of the engine and various phenomena occurring within the combustion chamber, it is necessary to provide a sensor that is directly positioned within the combustion chamber or in proximity to it and which senses the actual combustion process in the engine.
It has been understood that knocking can be determined by an optical sensor that operates within the combustion chamber and which senses the luminosity of the gases in that chamber. A type of engine sensor has been proposed that senses the luminosity of the gases within the combustion chamber. A variety of patents illustrating and describing the use of such sensors have issued including the following: 4,358,952; 4,369,748; 4,377,086; 4,393,687; 4,409,815; 4,412,446; 4,413,509; 4,419,212; 4,422,321; 4,422,323; 4,425,788; 4,468,949; 4,444,043; 4,515,132. For the most part, these patents disclose arrangements wherein the sensor is utilized to sense only total luminosity and to equate the luminosity signal to a knocking signal.
However, the inventors have determined that the measured luminosity in the combustion chamber alone or in combination with a pressure measurement can also be employed to determine the burned gas temperature in the combustion chamber. In addition, the inventors have found that the detected luminosity and pressure in the combustion chamber can be used to provide a determination of the trapped mass in the combustion chamber after each combustion cycle is completed, and to yield an estimate of NO.sub.x emissions from the engine.
It is, therefore, an object of this invention to provide an improved apparatus and method for operating an engine wherein the detected luminosity alone or in combination with the detected pressure in the combustion chamber can be used to determine the burned gas temperature in the combustion chamber.
It is a further object of this invention to provide an improved apparatus and method for operating an engine wherein the detected luminosity and pressure in the combustion chamber can be used to determine the trapped mass in the combustion chamber.
It is yet another object of this invention to provide an improved apparatus and method for operating an engine wherein the detected luminosity and pressure in the combustion chamber can be used to predict NO.sub.x emissions from the engine.
It is a still further object of this invention to provide engine control systems wherein the engine can be controlled in response to the determined burned gas temperature or trapped mass in the combustion chamber, or in response to the predicted NO.sub.x emissions. Once these combustion conditions are determined, various adjustable engine parameters such as air/fuel ratio, spark timing, fuel injection timing and pulse, and the like may be adjusted so as to obtain a desired value for these determined or predicted conditions in the engine.